JP4401540B2 - Laser apparatus and optical signal amplifying apparatus using the same - Google Patents

Laser apparatus and optical signal amplifying apparatus using the same Download PDF

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JP4401540B2
JP4401540B2 JP2000199397A JP2000199397A JP4401540B2 JP 4401540 B2 JP4401540 B2 JP 4401540B2 JP 2000199397 A JP2000199397 A JP 2000199397A JP 2000199397 A JP2000199397 A JP 2000199397A JP 4401540 B2 JP4401540 B2 JP 4401540B2
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optical fiber
laser
excitation light
optical
active substance
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JP2002026431A (en
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勝久 伊東
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浜松ホトニクス株式会社
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06Construction or shape of active medium
    • H01S3/063Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067Fibre lasers
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06Construction or shape of active medium
    • H01S3/063Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067Fibre lasers
    • H01S3/06704Housings; Packages
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06Construction or shape of active medium
    • H01S3/063Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
    • H01S3/067Fibre lasers
    • H01S3/06708Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09Processes or apparatus for excitation, e.g. pumping
    • H01S3/091Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094003Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light the pumped medium being a fibre
    • H01S3/094019Side pumped fibre, whereby pump light is coupled laterally into the fibre via an optical component like a prism, or a grating, or via V-groove coupling
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/14Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16Solid materials
    • H01S3/163Solid materials characterised by a crystal matrix
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01SDEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/14Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16Solid materials
    • H01S3/17Solid materials amorphous, e.g. glass

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser device and an optical signal amplifying device, and more particularly, to a laser device that performs laser oscillation by introducing excitation light into a laser active substance contained in an optical fiber, and an optical signal amplifying device using such a laser device. .
[0002]
[Prior art]
In the field of optical communication or optical processing technology, development of an inexpensive and high-power laser device is desired. Conventionally, an optical fiber laser device is known as a device that is highly likely to satisfy this requirement. The optical fiber laser device increases the interaction between the laser active substance and the light by confining the light at high density, and the interaction length can be increased by increasing the length, thus generating high-quality laser light spatially. be able to.
[0003]
In such a laser apparatus, in order to realize high output or high efficiency of laser light, it is a problem how to efficiently introduce excitation light into a core to which a laser active substance of an optical fiber is added. However, since the core diameter is normally limited to a few tens of μm or less when the core is set to the single-mode waveguide condition, it is difficult to efficiently introduce the excitation light into the end face of this diameter. In view of this, there has been proposed a laser apparatus capable of increasing the efficiency of introducing the excitation light by introducing the excitation light from the side surface of the optical fiber and enhancing the condensing property of the output laser light.
[0004]
For example, Japanese Patent Laid-Open No. 10-190097 forms a structure that is integrated with an optical medium in a state where optical fibers are densely packed. By irradiating excitation light from the periphery of this structure, the end face of the optical fiber is irradiated. A laser device that outputs laser light is disclosed. According to such an apparatus, since the excitation light is introduced from the side surface of the optical fiber, the area where the excitation light is introduced is much larger than when the excitation light is introduced from the end face. In addition, since the output laser light is only in a mode determined by the waveguide structure of the optical fiber, the output light from the optical fiber can be condensed to the core diameter approximately. Therefore, if the fiber propagates only in the single mode, the extracted light can be condensed up to the analysis limit. For this reason, it is possible to obtain laser light with a much higher luminance than the excitation light.
[0005]
[Problems to be solved by the invention]
However, in the laser apparatus described in Japanese Patent Laid-Open No. 10-190097, since the excitation light propagates across the optical fiber, it is necessary to prevent propagation attenuation and scattering loss of the excitation light in the gap between the optical fibers. For this reason, it is conceivable to integrate the optical fibers by heat fusion or to fill the gaps between the optical fibers with an organic adhesive.
[0006]
Although it is relatively easy to embed the gap between the optical fibers with an organic adhesive, the light resistance is low because of the organic material, and the mechanical strength cannot be maintained under strong excitation of several hundred W or more. May denature and become unable to maintain transparency.
[0007]
Further, the method of integrating the optical fibers by heat fusion is to completely fill the gaps between the optical fibers with the same glass as the optical fiber base material. Although this method is highly reliable, when the optical fiber is formed of glass having a high melting point such as quartz glass, it is necessary to melt the optical fiber at a high temperature of 1500 ° C. or higher, so that the core of the optical fiber may be deformed. In addition, there is a problem that it is difficult to develop an auxiliary jig for maintaining a shape that can withstand this temperature.
[0008]
The present invention has been made to solve the above-described problems, and is excellent in the efficiency of introducing excitation light and laser oscillation efficiency, and has high resistance to light and heat associated with laser oscillation, and is easy to manufacture. An object of the present invention is to provide an optical signal amplifying device using such a laser device.
[0009]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventor, as a result of earnest research, has an organic-inorganic hybrid material that has both the characteristics of an organic polymer resin that is easy to handle and the characteristics of an inorganic metal oxide glass that is excellent in light resistance and heat resistance. Found that it has excellent characteristics as an optical medium for fixing optical fibers in a dense state, thereby completing the present invention.
[0010]
  The present invention is made of glass having a refractive index of 1.60 or less, contains a laser active substance therein, and when the laser active substance is excited, at least a part of an optical fiber that emits laser light from an end is spiral or coiled An optical fiber structure fixed by an optical medium at adjacent portions of the optical fiber, and arranged around the optical fiber structure to excite a laser active substance contained in the optical fiber. In a laser apparatus having an excitation light source that emits excitation light and introducing the excitation light from the excitation light source into the optical fiber structure, the optical medium is poly (2-chloroethyl) silsesquioxane, poly (2-bromoethyl) ) Silsesquioxanes, mixtures thereof or oligos composed of these and polysiloxanes A laser device comprising a chromatography or polymer.
[0011]
  The present invention is made of glass having a refractive index of 1.60 or less, contains a laser active substance therein, and when the laser active substance is excited, at least a part of an optical fiber that emits laser light from an end is spiral or coiled An optical fiber structure fixed by an optical medium at adjacent portions of the optical fiber, and arranged around the optical fiber structure to excite a laser active substance contained in the optical fiber. In a laser apparatus having an excitation light source that emits excitation light and introducing the excitation light from the excitation light source into the optical fiber structure, the optical medium is poly (2-chloroethyl) silsesquioxane, poly (2-bromoethyl) ) Laser apparatus comprising amorphous silica cured with silsesquioxane or a mixture thereof A.
[0012]
In the present invention, the optical medium having the above-mentioned characteristics is represented by the general formula RSiO1.5(R represents an alkyl group, a hydroxyl group, a phenyl group, a vinyl group, a 2-chloroethyl group, a 2-bromoethyl group, hydrogen, deuterium, fluorine, or oxygen, except that R is all oxygen. May be different for each repeating unit.) An organic-inorganic hybrid material containing a repeating unit represented by:
[0013]
Specifically, the optical medium having the above characteristics includes polymethylsilsesquioxane, polymethyl-hydridosilsesquioxane, polyphenylsilsesquioxane, polyphenyl-methylsilsesquioxane, and phenylsilsesquioxane. Sun-dimethylsiloxane copolymer, polyphenyl-vinylsilsesquioxane, polycyclohexylsilsesquioxane, polycyclopentylsilsesquioxane, polyhydridosilsesquioxane, poly (2-chloroethyl) silsesquioxane, poly (2 -Bromoethyl) silsesquioxane, a mixture thereof or an oligomer or polymer comprising these and a polysiloxane, or poly (2-chloroethyl) silsesquioxane, poly (2-bromoethyl) silsesquioxane or Amorphous silica obtained by curing a mixture of al and the like.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 and 2 show a laser apparatus 10 according to a first embodiment of the present invention.
The laser device 10 includes an optical fiber structure 12 that is fixed in a state where an optical fiber 14 is wound, and an excitation light source 20 that emits excitation light that excites the optical fiber 14.
[0015]
The optical fiber structure 12 includes a single-layer spirally wound optical fiber 14 and an adhesive layer 16 for adhering and fixing adjacent portions of the optical fiber 14.
[0016]
The optical fiber 14 includes a core 14a doped with a laser active material, and a clad 14b formed around the core 14a. This laser active substance is a substance that generates laser light by a stimulated emission effect by excitation light, and is selected from rare earth elements such as neodymium (Nd), ytterbium (Yb), erbium (Er), etc. according to the use of the laser device Used. In the present embodiment, the optical fiber 14 is made of the clad 14b in order to reinforce the adhesive strength by the adhesive layer 16 and prevent the adhesive layer 16 from cracking due to shrinkage accompanying the hardening of the adhesive layer 16. In this case, a rectangular cross section is used. The optical fiber 14 is usually made of an optical material such as quartz glass, phosphate glass, fluoride glass, fluorophosphate glass, or borate glass with a refractive index of 1.60 or less. It is formed of a material according to the application.
[0017]
The optical fiber 14 is wound around a single layer spiral around a cylinder 22 having a reflecting surface on the outer periphery. One end of the optical fiber 14 is connected as a reflection end to the reflection mirror 24 inside the central body, and the other end is drawn out as an output end.
[0018]
Adhesive layers 16 are formed on adjacent portions of the wound optical fiber 14, and the optical fibers 14 are fixed as a disk-shaped optical fiber structure 12 by the adhesive layer 16. The adhesive layer 16 has a curing temperature of 400 ° C. or lower, and once cured, a thermal decomposition start temperature of 300 ° C. or higher, a refractive index of 1.40 to 1.56 at the wavelength of excitation light, and a loss of 0. An organic-inorganic hybrid polymer having a transparency of 5 dB / cm or less is used.
[0019]
As a substance having such characteristics, a general formula RSiO1.5(R represents an alkyl group, a hydroxyl group, a phenyl group, a vinyl group, a 2-chloroethyl group, a 2-bromoethyl group, hydrogen, deuterium, fluorine, or oxygen, except that R is all oxygen. May be different for each repeating unit.) An organic-inorganic hybrid polymer containing a repeating unit represented by: This organic-inorganic hybrid polymer is, for example, a highly crosslinked product obtained by hydrolyzing an organoalkoxysilane, and has a side chain of an organic substance in addition to a bond between a silicon atom and an oxygen atom inside the molecular structure. These form a three-dimensional network structure.
[0020]
Specifically, the organic-inorganic hybrid polymer having the above characteristics includes polymethylsilsesquioxane, polymethyl-hydridosilsesquioxane, polyphenylsilsesquioxane, polyphenyl-methylsilsesquioxane, phenyl. Silsesquioxane-dimethylsiloxane copolymer, polyphenyl-vinylsilsesquioxane, polycyclohexylsilsesquioxane, polycyclopentylsilsesquioxane, polyhydridosilsesquioxane, poly (2-chloroethyl) silsesquioxane, Examples include poly (2-bromoethyl) silsesquioxane, a mixture thereof, or a mixture of these and a polysiloxane.
[0021]
For example, when the laser active material is a substance having an excitation wavelength of about 0.910 μm such as ytterbium, in order to avoid absorption of excitation light due to stretching vibration of C—H bond at this wavelength, For example, hydridosilsesquioxane is used.
[0022]
The silsesquioxanes can be adjusted in refractive index in the range of 1.40 to 1.56 by changing the organic side chain. In addition, these oligomers can be mixed and polymerized to obtain an optically homogeneous polymer, whereby a polymer having a desired refractive index within the above range can be prepared. For example, polymethylsilsesquioxane whose organic side chain is all methyl group is 1.43 with a refractive index of sodium D line, and polyphenyl-methylsilsesquioxane whose side chain is composed of phenyl group and methyl group is The refractive index is 1.49. By mixing and polymerizing these oligomers, the refractive index of the quartz glass clad can be adjusted to 1.4585. In this way, by adjusting the refractive indexes of the clad 14b and the adhesive layer 16 of the optical fiber 14 to the same extent, the boundary between the adhesive layer and the clad is almost eliminated optically, and the scattering loss of the excitation light can be minimized. it can.
[0023]
Such an optical fiber structure 12 is obtained by applying a solution obtained by dissolving an oligomer or monomer of the above resin in an organic solvent such as butanol, acetone, methoxypropanol, pyridine, tetrahydrofuran, methyl isobutyl ketone, etc. After being wound around 22, the resin is cured by drying, heating, ultraviolet irradiation or the like. As a result, the adhesive layer 16 having high mechanical strength, transparency of loss of 0.5 dB / cm or less, and capable of withstanding a high temperature of 300 ° C. or higher for a long time can be formed.
[0024]
The thermal decomposition temperature of the resin is, for example, about 500 ° C for a 1: 2 mixture of polymethylsilsesquioxane and polyphenylmethylsilsesquioxane, and about 350 ° C for a phenylsilsesquioxane-dimethylsiloxane copolymer. is there. Β-Bromoethylsilsesquioxane starts to decompose at 300 ° C. or higher to form a dense inorganic film. The thermal decomposition temperature after becoming an inorganic film is 1500 ° C. or higher.
[0025]
When the resin is cured by heating, the curing temperature is 50 to 400 ° C., usually 100 to 250 ° C., and it can be cured at a temperature considerably lower than the temperature at which ordinary inorganic glass is melted and bonded. For example, poly (2-chloroethyl) silsesquioxane, poly (2-bromoethyl) silsesquioxane, and the like generate hydrogen chloride or hydrogen bromide during the heat polycondensation and serve as a polymerization catalyst by themselves. The release of the side chain is promoted, and an almost complete amorphous silica film is formed at a relatively low temperature of 400 ° C. or lower in an oxidizing atmosphere such as oxygen or ozone. Therefore, by using these substances, the optical fiber structure 12 made of a completely inorganic material having excellent light resistance and heat resistance can be produced at a relatively low temperature.
[0026]
In addition, poly (2-chloroethyl) silsesquioxane and poly (2-bromoethyl) silsesquioxane can form the above-described amorphous silica film by irradiating ultraviolet rays having a wavelength of 180 nm or more. The optical fiber structure 12 made of a completely inorganic material can be produced at room temperature.
If necessary, the optical fiber structure 12 is coated with a transparent resin layer 18 such as a fluororesin or an organic-inorganic hybrid material having a refractive index substantially equal to that of the clad 14 b of the optical fiber 14.
[0027]
An excitation light source 20 for exciting the optical fiber 14 to generate laser light is disposed around the optical fiber structure 12. As the excitation light source 20, light having a wavelength that excites a laser active substance doped in a core 14a of an optical fiber 14 such as a semiconductor element such as a light emitting diode (LED) or a laser diode (LD) or lamps such as a flash lamp. Is used.
[0028]
Hereinafter, the operation of the laser apparatus will be described.
Excitation light emitted from the excitation light source 20 is guided into the optical fiber structure 12 from a portion where a part of the transparent resin layer 18 is removed. The excitation light travels in the optical fiber structure 12 while traversing the side surface of the optical fiber 14, and is totally reflected by the transparent resin layer 18 due to the difference in refractive index between the transparent resin layer 18 and the clad 14b of the optical fiber 14. It is confined to the structure 12. At this time, according to the laser device according to the present invention, since the adhesive layer 16 is formed in the gap between the optical fibers 14 in the optical fiber structure 12, attenuation due to propagation of excitation light and the cladding 14b and the adhesive layer The scattering loss of the excitation light at the 16 interface surfaces can be reduced.
[0029]
This excitation light excites a laser active substance doped in the core 14a of the optical fiber 14, and generates laser light by a stimulated emission effect. This laser beam travels through the core 14a of the optical fiber 14 and is output from the output end.
[0030]
As described above, according to the laser device 10 of the present invention, it is possible to provide a laser device having excellent excitation light introduction efficiency and laser oscillation efficiency. In addition, the adhesive layer can be dried, heated at a relatively low temperature, or cured with ultraviolet rays, and once cured, it has high heat resistance, providing a laser device that is highly resistant to excitation light and easy to manufacture. It becomes possible to do.
[0031]
Next, another embodiment of the present invention will be described. In the following description, the same parts as those described above are denoted by the same reference numerals, and the description thereof is omitted.
3 and 4 show a laser device 30 according to a second embodiment of the present invention.
The laser device 30 includes an optical fiber structure 32 fixed in a state where the optical fiber 34 is wound, an excitation light source (not shown) that emits excitation light that excites the optical fiber 34, and the optical fiber structure 32. And a glass duct 40 as a light guide member for guiding the light.
[0032]
The optical fiber structure 32 has a structure in which an optical fiber 34 is wound in a coil shape. An adhesive layer 16 is formed on adjacent portions of the wound optical fiber 34, and the optical fiber 34 is fixed as a self-supporting cylindrical optical fiber structure 32 by the adhesive layer 16. In this embodiment, as the optical fiber 34, the adhesive strength of the adhesive layer 16 is enhanced, and in order to prevent the adhesive layer from cracking due to the shrinkage caused by the hardening of the adhesive layer 16, the cladding 34b A cross-sectional barrel shape having two parallel planes chamfered on the surface is used, and the optical fiber 34 is fixed by bonding the planes to each other. In such an optical fiber structure 32, for example, an optical fiber 34 is wound around a side surface of a cylindrical base without a gap, and an organic-inorganic hybrid material dissolved in an organic solvent is applied to the optical base 34 and cured by heating, ultraviolet irradiation, or the like. Later, it can be manufactured by removing the foundation.
[0033]
A glass duct 40 as a light guide member formed of a thin glass plate is provided on the upper end face of the optical fiber structure 32 to guide light emitted from the excitation light source. As the light guide member, a duct having another shape, an optical fiber, or the like may be used. Moreover, you may connect a light source directly to an optical fiber structure, without using a light guide member.
Such a laser device 30 can be operated even in a cooling medium having a lower refractive index than air or quartz, for example.
[0034]
Hereinafter, the operation of the laser device 30 will be described.
Excitation light emitted from the excitation light source is guided into the optical fiber structure 32 from above through the glass duct 40. The excitation light travels downward in the optical fiber structure 32 while traversing the side surface of the optical fiber 34. At this time, according to the laser device 30 according to the present invention, since the adhesive layer 16 is formed in the gap between the optical fibers 34, attenuation due to propagation of excitation light or excitation at the boundary surface between the clad 34 b and the adhesive layer 16. Light scattering loss is reduced.
[0035]
This excitation light excites the laser active substance doped in the core 34a of the optical fiber 34, and generates laser light by the stimulated emission effect. This laser beam travels through the optical fiber 34 and is output from the output end.
Thus, according to the laser device 30 of the present invention, it is possible to provide a laser device that is excellent in excitation light introduction efficiency and laser oscillation efficiency, highly resistant to excitation light, and easy to manufacture.
[0036]
Next, a third embodiment of the present invention will be described.
5 and 6 show a laser apparatus 50 according to a third embodiment of the present invention.
The laser device 50 has an optical fiber structure 52 fixed in a state where a plurality of optical fibers 14 are folded back and bundled, and an optical for holding the optical fiber structure 52 and introducing excitation light into the optical fiber structure 52. And a substrate 54.
[0037]
In this optical fiber structure 52, a plurality of optical fibers 14 forming one optical path are folded back, and a central portion thereof forms a bundle portion 56 in which the optical fibers 14 are bundled in parallel. In the bundle portion 56, an adhesive layer 16 is formed on adjacent portions of the optical fiber 14, and the optical fiber 14 is fixed as a structure by the adhesive layer 16. The bundle portion 56 is fixed by an adhesive layer 16 on an optical substrate 54 formed of glass or the like. End surfaces 54a and 54b of the optical substrate 54 are polished surfaces into which excitation light can be introduced.
[0038]
In such a laser device 50, a plurality of optical fibers are arranged on the optical substrate 54 without a gap, and an organic-inorganic hybrid polymer dissolved in an organic solvent is applied to the optical substrate 54 so as to penetrate between the optical fibers and between the optical fibers and the optical substrates. After being cured, the end faces of the optical fibers can be manufactured by connecting them with a fusion splicer so that the optical paths are connected. It is also possible to manufacture a single optical fiber by folding it in a plurality of times and bundling its central part and fixing the bundled part on an optical substrate using an adhesive layer.
[0039]
Hereinafter, the operation of the laser device 50 will be described.
Excitation light emitted from the excitation light source is guided into the optical substrate 54 from the end face 54b. The excitation light travels while being repeatedly reflected on the upper and lower surfaces of the optical substrate 54, but when reaching the portion where the bundle portion 56 is provided, it is introduced into the optical fiber 14 from the side surface via the adhesive layer 16. At this time, according to the laser device 50 according to the present invention, the attenuation of the excitation light in the adhesive layer 16 and the scattering loss of the excitation light at the boundary surface can be reduced.
[0040]
This excitation light excites a laser active substance doped in the core 14a of the optical fiber 14, and generates laser light by a stimulated emission effect. This laser beam is output from the end portion that is transmitted to the outside through the optical fiber 14.
As described above, according to the laser device 50 of the present invention, it is possible to provide a laser device that is excellent in excitation light introduction efficiency and laser oscillation efficiency, highly resistant to excitation light, and easy to manufacture.
[0041]
The present invention is not limited to the embodiment described above, and can be implemented with appropriate modifications within a range not departing from the gist thereof. For example, when a material having a small thermal shrinkage is used as the adhesive layer 16, an optical fiber having a clad having a circular or elliptical cross section can be used. Further, when the laser devices 10, 30, and 50 according to the present invention are used as an optical signal amplifying device, both ends of the optical fibers 14 and 34 are pulled out, one end is a signal light input end, and the other end is a signal output end. Is done.
[0042]
【Example】
Examples of the present invention will be described below.
Example 1
Laser oscillation was performed by the laser apparatus shown in FIGS.
The optical fiber 14 is a silica glass fiber having a core diameter of 50 μm, a cladding diameter of 70 × 200 μm, and a numerical aperture of the core 14a having a rectangular cross section, and 1.0 at% neodymium ions (Nd) in the core 14a.3+) Was doped 120 m. While the optical fiber 14 is wetted with a 10 wt% acetone solution of a 1: 2 mixture of polymethylsilsesquioxane and polyphenyl-methylsilsesquioxane, the inner diameter of the cylinder 22 with a gold plating on the surface is 200 μm wide. A structure was prepared by winding the layers so as to overlap each other, and dried in a clean atmosphere.
[0043]
After drying is completed, this structure is placed in an oven, heated to 110 ° C. at a heating rate of 1 ° C./min, held in this state for 30 minutes, and then to room temperature at 10 ° C./min. Cooled down. Remove the structure from the oven, wipe off excess silsesquioxane around the structure with water containing 10% ethanol, and after drying, place it in the oven again and heat at 200 ° C at a rate of 5 ° C / min. The temperature was raised to 30 minutes and kept in this state for 30 minutes. By this operation, the polysilsesquioxane was completely cured.
[0044]
A winding start portion of the optical fiber 14 was inserted into a slit formed in the cylinder 22, and a reflection mirror 24 reflecting 99% of light having a wavelength of 1.06 μm was attached to this end face as a reflection end. Further, the other end of the optical fiber 14 was left as a broken surface as an output end and pulled out to the outside. This structure was coated with a transparent fluororesin 18 having a refractive index of 1.33 to obtain an optical fiber structure 12.
[0045]
Around the optical fiber structure 12, 23 LDs 20 with an oscillation wavelength of 0.8 μm were arranged, and excitation light from each LD 20 was introduced through a light guide duct, about 120 W, a total of about 2760 W. As a result, laser oscillation in the wavelength 1.06 μm band of about 800 W from the output end of the optical fiber 14 was confirmed. Moreover, damage to the optical fiber structure 12 due to this laser oscillation was not observed.
[0046]
As a comparative example, a laser device was manufactured under the same conditions as in the above example except that an epoxy adhesive was used instead of polysilsesquioxane, and laser oscillation was performed. A part of the adhesive layer was burned with the following excitation power.
[0047]
In addition, a laser apparatus was produced under the same conditions as in the above example except that fused optical fibers were fused using quartz glass instead of polysilsesquioxane, and laser oscillation was performed. In this case, the damage due to the excitation light did not occur up to the maximum output as in the above example, but the propagation loss of the laser light propagating through the core was large, and the efficiency was only about 70% of the above example. From the above, the effects of the present invention were clear.
[0048]
Example 2
Laser oscillation was performed by the laser apparatus shown in FIGS.
The optical fiber 34 is a quartz glass fiber having a barrel-shaped cross-section in which two rows of planes are chamfered in parallel with intervals of 200 μm and 125 μm in diameter, having a core diameter of 50 μm, a core numerical aperture of 0.2, a core The total length of 50 m was prepared by doping 0.1 at% neodymium ions.
[0049]
The optical fiber 34 was wound around a cylinder having an inner diameter of 150φ so that the flat surfaces were in contact with each other. Two glass ducts 40 made of quartz glass having a thickness of 125 μm and a width of 12 mm were installed on the optical fiber 34. Thereafter, a solution of β-bromoethylsilsesquioxane in 5% by weight of methoxypropanol is sufficiently applied to the contact surface between the flat surfaces of the optical fiber 34 and the contact surface of the optical fiber 34 and the glass duct 40, and the solution is sufficiently applied in a clean atmosphere. Dried.
[0050]
Thereafter, excess β-bromoethylsilsesquioxane adhering to the surface was wiped off, and ultraviolet rays were irradiated for 4 hours with a low-pressure mercury lamp. The β-bromoethylsilsesquioxane was completely cured by this ultraviolet irradiation. Thereafter, the column was extracted to obtain a self-supporting cylindrical optical fiber structure 32.
A reflection mirror 24 that reflects 99.9% of light having a wavelength of 1.06 μm was attached to one end face of the optical fiber 34 as a reflection end. The other end of the optical fiber 34 was left as a broken surface as an output end.
[0051]
One LD with an oscillation wavelength of 0.8 μm was installed per one glass duct 40, and excitation light was irradiated from each LD at about 100 W for a total of about 200 W. As a result, laser oscillation in the wavelength 1.06 μm band of about 80 W from the output end of the optical fiber 34 was confirmed. Damage to the optical fiber structure 32 due to this laser oscillation was not observed.
[0052]
Example 3
Laser oscillation was performed by the laser apparatus shown in FIGS.
The optical fiber 14 is a silica glass optical fiber having a core diameter of 50 μm, a cladding diameter of 125 × 200 μm, and a numerical aperture of 0.2 of the core 14a and having a square cross section, and 2.0 at% neodymium ions (Nd) inside the core 14a.3+) Is doped with a length of 1 to 2 m and a total length of 20 m. As the optical substrate 54, a quartz glass flat plate having a length of 1.0 m, a width of 1.5 mm, and a thickness of 150 μm and having both end surfaces in the length direction polished was prepared. On this optical substrate 54, the optical fiber 14 was arranged along the longitudinal direction without any gap. A 20 wt% butanol solution of phenylsilsesquioxane-dimethylsiloxane copolymer was applied onto the optical fiber 14, and the optical fiber 14 and the contact surface between the optical fiber 14 and the optical substrate 54 were infiltrated, and dried in a clean atmosphere. Thereafter, excess phenylsilsesquioxane-dimethylsiloxane copolymer adhering to the surface of the optical fiber 14 was wiped off and cured by heating at 120 ° C. for 90 minutes.
[0053]
Thereafter, the end faces of the optical fibers 14 were connected by a fused fusion machine of quartz fibers so that the optical paths were connected. It was confirmed that the connection loss at a wavelength of 1.06 μm due to fusion splicing was only about the measurement error. Both ends of the optically connected optical fiber 14 were pulled out to the broken surface.
Excitation light of a laser diode having an oscillation wavelength of 0.8 μm was irradiated from both end faces in the longitudinal direction of the optical substrate 54 for 40 W per one end face in total 80 W. As a result, laser oscillation in a 1.06 μm wavelength band of about 32 W in total was confirmed from both end faces of the optical fiber 14.
Damage to the optical fiber structure 52 due to this laser oscillation was not observed.
[0054]
【The invention's effect】
As is apparent from the above description, according to the present invention, the optical medium for fixing the optical fiber can be cured at a temperature lower than that of ordinary inorganic glass such as 400 ° C. or lower, which facilitates the manufacture of the laser device. There is no risk of deforming the core of the optical fiber during manufacture. In addition, since this optical medium has a heat resistance of 300 ° C. or higher once cured, it is not damaged by light and heat accompanying laser oscillation. In addition, since this optical medium has a refractive index of 1.40 to 1.56 at the wavelength of the excitation light that can excite the laser active substance, it becomes possible to set the refractive indexes of the optical fiber and the optical medium to the same level. The scattering loss of the excitation light at the boundary between the optical medium and the cladding can be minimized. Furthermore, since this optical medium has high transparency such as a loss of 0.5 dB / cm, it is possible to prevent attenuation of excitation light in the optical medium.
Therefore, according to the present invention, it is possible to provide a laser device that is excellent in excitation light introduction efficiency and laser oscillation efficiency, has high resistance to excitation light, and is easy to manufacture, and an optical signal amplification device using this laser device. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing a first embodiment of a laser apparatus according to the present invention.
FIG. 2 is a sectional view schematically showing a first embodiment of a laser apparatus according to the present invention.
FIG. 3 is a perspective view schematically showing a second embodiment of the laser apparatus according to the present invention.
FIG. 4 is a cross-sectional view schematically showing a second embodiment of the laser apparatus according to the present invention.
FIG. 5 is a perspective view schematically showing a third embodiment of the laser apparatus according to the present invention.
FIG. 6 is a sectional view schematically showing a third embodiment of the laser apparatus according to the present invention.
[Explanation of symbols]
10 Laser equipment
12 Optical fiber structure
14 Optical fiber
14a core
14b cladding
16 Adhesive layer
20 Excitation light source
30 Laser equipment
32 Optical fiber structure
34 Optical fiber
34a core
34b cladding
40 Glass duct
50 Laser equipment
52 Optical fiber structure

Claims (4)

  1. It consists of glass with a refractive index of 1.60 or less, contains a laser active substance inside, and when the laser active substance is excited, at least a part of an optical fiber that emits laser light from its end is wound in a spiral or coil shape An optical fiber structure fixed by an optical medium in adjacent portions of the optical fiber in a dense state,
    In the laser apparatus that is disposed around the optical fiber structure, has an excitation light source that emits excitation light that excites a laser active substance contained in the optical fiber, and introduces excitation light from the excitation light source into the optical fiber structure .
    The optical medium includes a laser device including an oligomer or a polymer including poly (2-chloroethyl) silsesquioxane, poly (2-bromoethyl) silsesquioxane, a mixture thereof, or a mixture of these and polysiloxane.
  2. It consists of glass with a refractive index of 1.60 or less, contains a laser active substance inside, and when the laser active substance is excited, at least a part of an optical fiber that emits laser light from its end is wound in a spiral or coil shape An optical fiber structure fixed by an optical medium in adjacent portions of the optical fiber in a dense state,
    In the laser apparatus that is disposed around the optical fiber structure, has an excitation light source that emits excitation light that excites a laser active substance contained in the optical fiber, and introduces excitation light from the excitation light source into the optical fiber structure .
    The optical medium includes a laser device including amorphous silica obtained by curing poly (2-chloroethyl) silsesquioxane, poly (2-bromoethyl) silsesquioxane, or a mixture thereof.
  3.   The laser device according to claim 1, wherein a flat surface is formed on a side surface of the optical fiber, and the optical fiber is fixed in a state where the flat surfaces are in close contact with each other.
  4.   An optical signal amplifying device comprising the laser device according to claim 1, wherein one end of an optical fiber of the laser device is an input end of signal light, and the other end is an output end of amplified light.
JP2000199397A 2000-06-30 2000-06-30 Laser apparatus and optical signal amplifying apparatus using the same Expired - Fee Related JP4401540B2 (en)

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US09/888,500 US6798792B2 (en) 2000-06-30 2001-06-26 Laser device and light signal amplifying device using the same
DE2001131661 DE10131661B4 (en) 2000-06-30 2001-06-29 Laser device with an optical fiber and this employing, a light signal amplifying device

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